<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <script>
        alert('文本')//窗口弹出
    console.log(12)//控制台输出，一般程序员调用使用，页面不会显示
   
    var a = prompt('请输出字','a');
    console.log(a)
    console.log(typeof a) //数据类型为字符串string

    </script>
</body>
</html>